With development in technology, various smart image capturing devices, such as tablet computers, personal digital assistants and smart phones, have become indispensable tools for people nowadays. Camera lenses equipped in high-end smart mobile image capturing devices provide same or better specifications than those of traditional consumer cameras, and some even provide three-dimensional image capturing features or near-equivalent pixel qualities to those of digital single lens reflex cameras.
Ideally, two optical axes of a dual-lens module are supposed to be parallel to each other, and two lens centers are supposed to be perpendicular to a plane formed by the two optical axes. However, the optical axes and the lens centers are all invisible, and thus it is difficult for an inspector to ensure that the optical axes and the lens centers are precisely positioned in an assembly stage during manufacture.